[Hearing Loss and Speech Recognition in the Elderly]

Abstract

Elderly people often complain about poor speech understanding in noisy environments. In clinical practice, speech tests under noise conditions are used to examine hearing ability. The HÖRSTAT study, conducted on a population-based random sample consisting of 1903 adults, used the Goettingen Sentence Test (GÖSA) under noise conditions along with pure-tone audiometry. Hearing impairment was defined as pure-tone average at 0.5, 1, 2 and 4 kHz (PTA-4) greater than 25 dB HL in the better ear (WHO criterion). As expected, pure-tone thresholds and speech recognition thresholds (SRT) in GÖSA worsened steadily with age. For a comparison of PTA-4, SRTGÖSA and self-reported hearing, analysis was limited to 553 adults aged 60-85 years with PTA-4 below 50 dB HL and SRTs measured with a constant 65 dB SPL noise level. The percentage of hearing-impaired increased from 13 % in the 60-65 year-old people to 60 % in those aged 80-85 years. Overall, 68 % of the 60-85 years adults showed normal hearing in terms of unimpaired hearing according to the WHO criterion. The SRTGÖSA of 66 % of the elderly adults with normal hearing, however, did not lie within the reference range established with young normal hearing subjects in the HÖRSTAT study (4.8 ± 1.8 dB SNR, mean±2 * standard deviation). Among the 553 elderly, only 24 % reached this reference range. PTA-4 and SRTGÖSA results showed moderate to good correlations (Pearson r = 0.562, within 5-years bands: 0.372-0.514). From PTA-4 ≥ 30 dB HL and SRTGÖSA ≥- 2 dB SNR, respectively, more than half of the subjects reported hearing difficulties. Despite the continuous decline of PTA-4 and SRTGÖSA with age, the proportion of self-reported hearing difficulties as well as the self-rated hearing ability score stagnated. From the age of 70 years onwards, the elderly in the HÖRSTAT sample tend to overestimate their hearing abilities and to underestimate their difficulties.